Tilt-up concrete wall panel construction has been used for years to construct commercial buildings such as warehouses, factories, and the like. In general, such construction entails building a rectangular concrete form, usually on site, placing steel reinforcing bars (rebar) or other reinforcement in the form, filling the form with concrete, and, after the concrete cures, tilting the resulting concrete panel into place to form a wall section. Numerous wall sections generally are fabricated and attached together and to framing members of the building to form complete walls. Utility conduits may be embedded within the wall sections as needed to provide for electricity and plumbing. U.S. Pat. Nos. 3,394,523 of Sackett, 4,104,356 of Deutsch et al., 3,604,174 of Nelson, and 4,856,244 of Clapp disclose various examples of tilt-up concrete wall panel construction techniques.
While traditional concrete wall panel construction techniques have been somewhat successful in construction commercial buildings, they nevertheless have been fraught with a variety of inherent problems and shortcomings. Among these are the fact that, in most cases, the forms into which the concrete is poured usually are fabricated from wood or metal on site at a worksite such as, for example, on the ground adjacent to where they are to be tilted up to form a wall. The on-site building of such forms is a tedious and time consuming process and further requires a high level of skill on behalf of workers to assure that the panels are all the correct size and configuration. In additional, where wooden forms are used, the process of disassembling the framing members and discarding them after the concrete cures can be time consuming and wasteful. In most cases, reinforcing stakes, spacers, or blocks must be used to reinforce the sides of the concrete forms so that they do not bow outwardly or otherwise deform under the substantial pressures created by the wet concrete poured into the forms. Installing theses reinforcing members is yet another time consuming step in the process.
Another problem with prior art techniques relates to the installation within the concrete forms of the rebar, wire mesh, or other reinforcing members that are to be embedded within the finished wall sections. More particularly, the construction of a matrix of reinforcing members is a time consuming and tedious process. This is particularly true in systems where the walls of the form are made from inwardly open channel shaped steel or formed sheet metal. The reason is that the reinforcing members must be installed in the mid-portion of the form between the inwardly projecting lips of the walls. In order the accomplish this, the framing members must be cut to be longer than the distance between the facing edges of opposed lips and jockeyed into place in the middle of the form before being secured in place within the form.
Typical of the current art form, concrete wall panels are anchored by the use of threaded dowel rods and/or steel weld plates which are positioned in the wall panel prior to placing concrete and then after concrete placement a portion of the anchor is left exposed from the concrete to allow for the alignment with an adjoining anchor to connect the panel in place. Anchor dowels and/or plates are applied to the panel at the job site, frequently at the time of concrete placement. This results in the negative occurrences of inaccurate anchor placement, the need for extremely accurate anchor positioning for alignment, omission of anchors, anchors covered by or lost within concrete, and the need for special welding equipment with specially skilled field welding techniques.
There exists a need for an improved tilt-up concrete wall form and a method of fabricating concrete wall sections using the form that addresses and solves the above mentioned and other problems of the prior art. The form should be lightweight, strong, and portable so that they can be manufactured to exacting tolerances at a remote location and delivered to a job site on a truck for immediate use. The form assembly should also increase efficiency and accuracy of wall panel installation while minimizing construction mistakes and waste. Further, the form should be usable without the need for any on-site form construction and without the need to reinforce the walls of the form against bowing under pressure when concrete is poured into the form. No deconstruction of the form should be required after the concrete cures and no wasted that requires disposal should be generated during use of the form. At a remote form fabrication facility, fabrication should be quick and efficient and the installation of a matrix of reinforcing rebar in the mid-portion of the form should be accurate, quick, and efficient while also providing exacting and labor-saving structural anchor points. An improved method of fabricating the tilt-up concrete wall sections using such an enhanced form also should be included. It is to the provision of such a form and method of construction that the present invention is primarily directed.